Refrigerating apparatus



March 13, 1956 R. CURELL, JR 2,737,789

REFRIGERATING APPARATUS Filed March 8, 1952 4 Sheets-Sheet l IN VEN TOR.

RANDAL 6URLL,JK.

March 13, 1956 CURELL, JR

REFRIGERATING APPARATUS 4 Sheets-Sheet 2 Filed March 8, 1952 m m m m IMMIML CUREU R BY g March 13, 1956 R CURELL, JR

REFRIGERATING APPARATUS 4 Sheets-Sheet 3 Filed March 8, 1952 FDOFDU INVENTOR. RANDAL C UREL L,JR.

March 1956 R. CURELL, JR

REFRIGERATING APPARATUS 4 Sheets-Sheet 4 Filed March 8, 1952 UXOIU ml INVENTOR.

RANDAL CURELL,JR.

BY I

United States Patent REFRIGERATING APPARATUS Randal Curell, Jr., Cincinnati,

Industries, Inc., Ohio Application March 8, 1952, Serial No. 275,629

11 Claims. (Cl. 624) This invention relates to refrigerating apparatus and more particularly to apparatus for use in cooling air for airplanes and the like.

It is an object of this invention to provide a self-contained, portable, air conditioning unit which is complete with its own power system.

Another object of this invention is to provide a selfcontained air conditioning unit which is sufficiently compact to be mounted on a pair of Wheels and pulled around either by hand or by a jeep'or the like.

Another object of this invention is to provide an improved towbar which is permanently attached to the unit but which swings out of the way when not in use.

Still another object of this invention is to provide a selfcontained air conditioning unit in which the evaporator and evaporator fan may be lifted into a plane or the like and in which they are connected to the rest of the system by means of a specially constructed combination cable and conduit.

It has been standard practice in units of this general type to make the suction line, liquid line, and the electric cable as separate elements, each leading from the evaporator assembly to the condensing unit which is mounted in a truck. The problem of coiling and uncoiling these three separate elements was always quite a problem. It is an object of this invention to provide a single molded conduit having a first passage for the liquid refrigerant, a second passage for the vaporized refrigerant, and electric conductors embedded in the walls of said passages.

Still another object of this invention is to provide an improved control system for regulating the operation of the air conditioning equipment.

More particularly, it is an object of this invention to provide an improved starter and generator arrangement in which the fields of these are connected in parallel for starting purposes but are connected in series for generating purposes.

Other objects and advantages reside in the construction of parts, the combination thereof and the mode of operation, as will become more apparent from the following description.

In the drawings:

Figure 1 is a perspective view of a self-contained air conditioning unit embodying my invention;

Figure 2 is a fragmentary sectional view showing the cross sectional construction of the conduit which connects the evaporator and evaporator fan unit to the rest of the equipment;

Ohio, assignor to Keco Cincinnati, Ohio, a corporation of Figure 3 is a perspective view of the unit showing the evaporator removed. Dotted lines are used to indicate the position of the evaporator when mounted on the main carriage;

Figure 4 is a view showing the evaporator assembly;

Figure 5 is a wiring diagram, partly schematic, showing the controls;

Figure 6 is a schematic view showing the refrigerant circuit and showing the relationship between the cranking motors, the main engine and the compressor; and

Figure 7 is a fragmentary schematic view showing an alternative arrangement for reconnecting the windings of a motor or generator unit when using only one such unit.

Air conditioning units of the type" disclosed herein are used by the armed services for air conditioning the interior of airplanes and the like. The unit must, therefore, be self-contained and complete in every respect and must be readily transportable, so that it may be pulled by hand or behind a jeep or the like for movement to and from planes. The only portion of the unit which is mounted in the plane during the process of conditioning the air in the plane is the evaporator and the evaporator fan means. It is also important that a unit of this type be troublefree, efficient and convenient in operation.

Referring now to the drawings wherein I have shown a preferred embodiment of the invention, reference numeral 10 designates a main frame or chassis mounted on a pair of wheels 12 whereby the unit is rendered readily transportable. As best shown in Figures 1 and 3 of the drawings, a drawbar 14 is provided for attaching the unit behind a jeep or the like. The air conditioning units previously used by the Air Corps were provided with detachable drawbars which were so designed that it was necessary to disconnect the drawbar from the chassis for space conservation purposes when the drawbar was not in use. With such an arrangment, the drawbars were frequently misplaced or lost. In the construction shown, the drawbar 14 has its one end rigidly attached to a vertical swivel post 16 which is rotatably supported on the frame 10 adjacent the one front corner of the frame, so that the drawbar may be swung out in front of the unit or may be folded up alongside the unit, as shown in Figure 3. A brace 18 is pivotally secured to the front end of the drawbar 14, as shown, and is provided with a depending lug 20 at its free end which is adapted to engage a stationary loop 22 when the drawbar is not in use and is adapted to engage a loop 24 for holding the drawbar in operative position. By virtue of the above described arrangement, it is obvious that the drawbar can never be lost and may quickly be shifted from its operative position to its inoperative position.

The arrangement of the parts on the chassis It is such that the weight is properly distributed and the parts are compactly and eliiciently arranged. The refrig crating equipment used for cooling the air consists of a condenser 30 supported directly on the lower shelf-like portion of the frame 10 adjacent the front end of the unit. A compressor 32 is also supported directly on the upper shelf-like portion of the main frame 10 and is adapted to be driven by an air cooled gasoline engine generally designated by the reference numeral 34. The engine 34 is a self-contained engine which is adapted to be mounted on the lower rear portion of the frame or carriage 10, as best shown in Figure l. A first fan 35" connected to one end of the engine shaft circulates cooling air over the engine 34. A second fan 36 is provided on the other end of the engine shaft for circulating condenser cooling air in thermal exchange relationship with the condenser 30. The chassis is preferably made of angle iron material and includes lower and upper angle iron shelf-like supports which have been designated by the reference characters 11 and 13 respectively. A pair of storage batteries 38 is mounted on the frame 10 directly above the condenser 30. A control box 40 is also supported on the frame 10 and serves to enclose the major portion of the electrical controls, such as the voltage regulator and reverse current relay and other relays as those shown in Figure 5 of the drawings. The upper rear portion of the main frame 10 comprises a pair of angle iron brackets 42 on which the evaporator unit 44 may be placed when not in use. By virtue of the above distribution of the various elements on the main frame 10, the parts fit together very compactly and the weight is well balanced with respect to the supporting wheels 12 so as to make it easy for one to push the unit around by hand.

A protective cover or shield 46 is provided, as best shown in Figure 3, for covering the battery terminals. This shield may be lifted from the batteries for inspection and maintenance of the batteries. Another purpose of the cover 46 is to provide a shelf or support for the conduit 48 which connects the evaporator unit to the rest of the equipment.

The refrigerant circuit is a conventional circuit in every respect except that the liquid and suction lines connecting the evaporator to the condenser and the compressor have been combined into a single conduit 48, as best shown in Figure 2 of the drawings. A bypass has been provided between the suction and discharge sides of the compressor in which a compressor unloader valve 124 (see Figures 5 and 6) has been provided. This valve is opened when the solenoid 126 is energized, as will be explained hereinafter. The conduit 48 includes a small inner tube 50 which serves as a liquid line and which is disposed within an outer tube 52 which serves as a suction line and a housing for the inner tube 50. Any suitable plastic material may be used for making the tubes 50 and 52. It has been found that vinylidene chloride is especially suitable for use in manufacturing the inner tube 50 and chloroprene (commonly known as neoprene) is suitable for the outer tube. By placing the relatively high pressure liquid line 50 within the tube 52, one not only protects the tube 50 from injury, but one also reduces the pressure differential acting on the walls of the tube. Furthermore, any liquid refrigerant which might leak through the tube 58 would not be lost.

By virtue of the above described arrangement, the liquid refrigerant flowing to the evaporator flows in thermal exchange relationship with the relatively low temperature refrigerant vapor returning from the evaporator to the suction inlet of the compressor. In order to reinforce the outer tube 52 and in order to provide electrical connections to electrical devices on the evaporator assembly, there have been embedded two sets of electric conductors 56 within the outer tube 52, as shown. These conductors supply electricity to the evaporator fan motors 54 and to the evaporator thermostat 80 (see Figure 5 As explained more fully hereinafter, the air conditioning system is automatically controlled by starting and stopping the engine in response to air conditioning requirements. Rather than using a conventional cranking motor and generator unit with its many limitations, the system uses two such units and includes means whereby a heavy starting current is used in the fields and a much lighter current flows through the field windings when the unit is used as a generator. The control circuit has been designed to provide good voltage regulation at low field excitation. The main engine is of the constant speed type and consequently the generators normally operate at a constant speed.

Referring now to Figure 5 of the drawings wherein I have shown a preferred embodiment of the electrical system for use in controlling the apparatus, reference numerals 58 and 60 designate a pair of dynamoelectric machines which serve as starting motors and also serve as generators. The motor 58 is provided with a series field 62 and a shunt field 64, whereas the motor 68 is provided with a series field 66 and a shunt field 68. Both of these starting motors are controlled by a main power switch 70 which is under control of the solenoid 72.

The system may be set for automatic operation or it may be manually controlled to either provide refrigeration or to provide defrosting. For this purpose a selector switch 74 is provided, as shown, and is adapted to be selectively moved into contact with any one of a plurality of contacts labeled D, A, M and S. When it is desired to cause the system to operate automatically, the

switch 74 is moved into engagement with the contact labeled A, with the result that a circuit is closed from the main power line 76 leading from the battery 33 through various controls which provide for automatic operation. Thus, the circuit is closed to the cranking limiter control 78, the air temperature responsive switch 80 and the solenoid 82, as shown, with the result that if the cranking limiter control switch is closed and the thermostat 80 calls for refrigeration, the solenoid 82 will be energized so as to close the switches 84 and 86. Closing of the switch 86 causes current to flow from the power line 76 through the air operated switch 98 to the starting solenoid 72, so as to cause the starter switch 70 to close. Closing of the switch 70 will cause the dynamoelectric machines 58 and 60 to operate as cranking motors until the engine starts. When the engine starts to operate under its own power, the condenser cooling fan 36 will cause the air switch 90 to move from the position in which it is shown in Figure 5 so that it will cause the cranking solenoid 72 to become deenergized and thereby open the switch 70.

When the system first calls for refrigeration, the unloader valve 124 is open as its operating solenoid 126 is energized through the switch 94. The valve 124 is a conventional unloader valve which is adapted to open a bypass between the inlet and the outlet of the compressor. Closing of the switch 84, in response to energization of the solenoid 82 causes the flow of current through the solenoid 92, thereby opening the switch 94 and closing the switches 96 and 98. Closing of the switch 96 causes current to flow to the evaporator fans 54 and the indicator light 100. Closing of the switch 98 serves to energize a holding circuit 182. Opening of the switch 94 deenergizes the unloading solenoid 126 which operates the valve 124.

The air operated switch 90 normally remains in its upper position, as shown in Figure 5, when the engine is at a standstill or is merely being rotated at a slow speed by the cranking motors 58 and 60. However, when the engine starts operating under its own power, the air flowing against the vane 91 will cause the switch to move from its upper position to its lower position, so as to close the circuit to a field switching solenoid 164. The solenoid 104 controls the switching contactors 166, 108, and 112. When the contactor 186 is pulled up into its uppermost position, a holding circuit 114 becomes closed as shown. When the contcator 198 is in its lower- .most position, the field coils 64 and 68 of the motor are connected in parallel between the battery 38 and the ground 116, whereas when the switches 186, 119 and 112 are lifted, the fields 64 and 68 will be connected in series for generation purposes. Approximately four times as much current flows through the field windings when they are connected in parallel as when they are in series and consequently one obtains voltage regulation at low field excitation during the time when the system generates current.

So long as the selector switch 74 is set for automatic operation and the switches 78 and 80 are closed, current will be supplied to the choke 118 and ignition 120 of the engine through the automatic high-low pressure cutout switch 122. Inasmuch as the high-low pressure cutout switch 122, the cranking limiter switch 78 and the thermostatic switch 80 are all well known devices, the construction and operation of these devices will not be described in greater detail. The unloader valve 124 has been provided in the refrigerant system for unloading the system during the cranking operation of the motor. This unloader valve 124 is controlled by a solenoid 126, which in turn may be controlled by a manualy operated pushbutton switch 128. The circuit is normally closed through the push-button switch 128 when the selector switch 74 is set on an automatic operation and when the electric circuit calls for cranking of the engine. The switch 123 makes it possible to manually unload the compressor when the switch 94 is open.

For defrosting purposes the selector switch 74 is moved to the contactor designated by the reference character D. When the selector switch 74 is moved to the defrosting position, the refrigeration system is shut off, but the fan motor will continue to operate so as to cause air to flow over the evaporator. This flow of air over the evaporator, in the absence of refrigeration, will cause the ice to melt from the evaporator. If for any reason one wishes to manually start and stop the system, the selector switch 74 is moved to the terminal designated by the reference character M. A voltage regulator and reverse current relay 130 has been provided in the circuit as shown. This is a standard device commonly used for controlling the flow of current between the dynamoelectric machines and the battery. This voltage regulator includes the conventional voltage relay 132 and reverse current relay 134.

The system shown provides for automatic defrosting in that an excess accumulation of ice on the evaporator tends to insulate the evaporator, with the result that the pressure in the evaporator decreases to a point where the pressure operated cutout 122 interrupts the flow of current to the ignition system of the engine. This then causes the engine to stop, but as indicated by the circuit in Figure 5, the evaporator fans will continue to operate and thereby defrost the evaporator.

In Figure 5 of the drawings there is shown a circuit arrangement which contemplates the use of two separate starting motor units wherein the field windings 64 and 68 of the two units are connected in parallel with one another when the units are used for starting, out are connected in series when the units are used for generating current. As pointed out herein above, this arrangement provides for a heavy starting current to fiow through the windings 64 and 68 during the relatively short period of time devoted to cranking the engine. This heavy current would be highly objectionable during the generating portion of the cycle, not only because of the excessive heating which would result from prolonged flow of a heavy current through these windings, but also because it is difficult, if not impossible to use a cheap voltage regulator for regulating the output of the generator when the field current is high.

While Figure 5 shows an arrangement in which the windings 64 and 68 constitute parts of separate dynamoelectric machines, the same desirable result can be obtained even when using a single cranking motor or generator by reconnecting different portions of the field windings, so that during the process of cranking the engine the various portions of the field windings are connected in parallel so as to draw a heavy current, whereas during generation these field windings are connected in series so as to cut down the flow of current.

In Figure 7 of the drawings there is shown a fragmentary circuit diagram illustrating how such a single machine could be substituted in the circuit shown in Figure 5 for the two machines 58 and 60. In this figure :1 single dynamoelectric machine 58' has been shown provided with two shunt field coils 64' and 68. These windings 64' and 68 would be connected in the circuit in the same manner as the windings 64 and 68 of Figure 5 are connected in the circuit. Thus, the single dynamoelectrie machine 58 shown in Figure 7 has been substituted for the two machines 58 and 60 shown in Figure 5 without making any other changes in the main circuit other than those indicated in Figure 7.

For purposes of illustration, Figure 7 shows a machine in which the shunt field winding includes two portions which may be connected either in series or parallel, whereas the shunt field winding could, for example, have four field coil portions, so that when the machine is used as a generator all four coils could be connected in series, but when the machine is used as a motor all four coils could be connected in parallel so as to draw a much heavier current.

By virtue of the above described construction, one obtains a portable, self-contained, system in which the engine is automatically started and stopped in response torefri'geration requirements and in which all of the connections between said evaporator,

controls are of the type which are inexpensive yet trouble-free in operation.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. In a portable self-contained refrigeration unit, a chassis, an engine mounted on said chassis, a compressor mounted on said chassis, power transmitting means between said engine and said compressor, a condenser mounted on said chassis, an evaporator, refrigerant flow connections between said evaporator, condenser and compressor, a first dynamoelectric machine mounted on said chassis, a second dynamoelectric machine mounted on said chassis, field windings in each of said dynamoelectric machines, means for selectively connecting said windings in series or parallel, power transmitting means between said engine and said dynamoelectric machines, a battery, means for supplying power from said battery to said field windings in parallel so as to cause said machines to serve as motors for cranking said engine, and means responsive to the predetermined increase in the speed of said engine for reconnecting said field windings in series so as to cause the same to serve as generators for charging said battery.

2. In a portable self-contained refrigeration unit, a chassis, an engine mounted on said chassis, a compressor mounted on said chassis, power transmitting means between said engine and said compressor, a condenser mounted on said chassis, an evaporator, refrigerant flow connections between said evaporator, condenser and compressor, dynamoelectric means mounted on said chassis, power transmitting means between said engine and said dynamoelectric means, a battery, circuit means including a voltage regulator and reverse current relay for connecting said battery to said dynamoelectric means, a first fan means for flowing air to be cooled in thermal exchange relationship with said evaporator, a second fan means operated by said engine for establishing an air stream, and means comprising an air flow responsive switch mounted in said air stream for connecting said first fan means in said circuit in response to a predetermined increase in the velocity of the air in said air stream.

3. In a portable self-contained refrigeration unit, a chassis, an engine mounted on said chassis, a compressor mounted on said chassis, power transmitting means between said engine and said compressor, a condenser mounted on said chassis, an evaporator, refrigerant fiow condenser and cornressor, a vertically extending swivel rod carried by said chassis, a towbar secured to said swivel rod, and means for selectively holding said towbar in a projected position in front of said chassis or for holding said towbar in a folded position adjacent one side of said chassis.

4. In a portable self-contained refrigeration unit, a chassis, an engine mounted on the rear of said chassis, a compressor mounted on said chassis, power transmitting means between said engine and said compressor, a condenser mounted at the front end of said chassis, an evaporator, refrigerant flow connections between said evaporator, condenser and compressor, a vertically extending swivel rod carried by said chassis, a towbar secured to said swivel rod, and means for selectively holding said towbar in a projected position in front of said chassis or for holding said towbar in a folded position adjacent one side of said chassis, said rod being disposed adjacent a forward corner of said chassis so as to serve as a protective bumper for said condenser.

5. In a portable refrigeration unit for conditioning air for an airplane or the like of the type'provided with a cart, refrigerant liquefying apparatus mounted on said cart, an evaporator apparatus removably supported on said cart for insertion into an airplane or the like, the combination comprising flexible refrigerant flow connections between said evaporator and said refrigerant liquefying apparatus including a liquid line and a suction line, said suction line comprising a flexible tubular conduit, said liquid line comprising a flexible tubular conduit disposed within said suction line whereby both of said conduits may be bent into coil formation as a single conduit when said evaporator is not in use and whereby the fluids flowing in said lines pass in thermal exchange relationship with one another, the suction line having reinforcements therein for maintaining rigidity thereof, said reinforcements including electrical conductor means embedded within said suction line.

6. In a portable refrigeration unit for conditioning air in an airplane or the like of the type provided with a cart, refrigerant liquefying apparatus mounted on said cart, an evaporator assembly removably supported on said cart for insertion into the space to be conditioned, the combination comprising flexible refrigerant flow connections between said evaporator assembly and said refrigerant liquefying apparatus including a liquid line and a suction line, said liquid line comprising a flexible tubular conduit disposed within said suction line whereby both of said conduits may be coiled as a single conduit when said evaporator assembly is not in use, said evaporator assembly including blower means for circulating air in thermal exchange relationship with said evaporator assembly and an electric motor means for operating said blower means, a source of electrical energy carried by said cart, and conductor means molded in said flexible conduit reinforcing said conduit and providing means for supplying electrical energy from said source of electrical energy to said motor means.

7. In a portable refrigeration unit for conditioning air in an airplane or the like of the type provided with a cart, refrigerant liquefying apparatus mounted on said cart, an evaporator assembly removably supported on said cart for insertion into the space to be condtioned, the combination comprising flexible refrigerant flow connections between said evaporator assembly and said refrigerant liquefying apparatus including a liquid line and a suction line, said liquid line comprising a flexible tubular conduit disposed within said suction line whereby both of said conduits may be coiled as a single conduit when said evaporator assembly is not in use, said evaporator assembly including blower means for circulating air in thermal exchange relationship with said evaporator assembly and an electric motor means for operating said blower means, a source of electrical energy carried by said cart, conductor means molded in said flexible conduit reinforcing said conduit and providing means for supplying electrical energy from said source of electrical energy to said motor means, said evaporator assembly including a temperature responsive switch for controlling the operation of said refrigerant liquefying apparatus in accordance with refrigeration requirements, and conductor means molded in said flexible conduit electrically connecting said switch to said refrigerant liquefying means.

8. In a portable self-contained refrigeration unit, a chassis having an upper frame member and a lower frame member, an engine mounted on said lower frame mem ber, a compressor mounted on said upper frame member, power transmitting means between said engine and said compressor, a condenser mounted on said lower frame member, an evaporator removably supported on said upper frame member, refrigerant flow connections between said evaporator, condenser and compressor, a first dynamoelectric machine mounted on said upper frame member adjacent one side of said compressor, a second dynamoelectric machine mounted on said upper frame member adjacent the other side of said compressor, power transmitting means between said engine and said dynamoelectric machines, a battery supported on said upper frame member, and circuit means including a voltage regulator and reverse current relay for connecting said battery to said dynamoelectric machines, said voltage regulator and reverse current relay being mounted on said upper frame'member.

9. In a refrigeration unit, an engine, a compressor, power transmitting means between said engine and said compressor, fan means operated by said engine for fiowing air over said engine, a condenser, an evaporator, refrigerant flow connections between said evaporator, condenser and compressor, means for cranking said engine, electrically operated valve means for unloading said compressor, and means for flowing air to be cooled in thermal exchange relationship with said evaporator, said last named means comprising an electric motor, a battery, an electric circuit including means for supplying electrical energy from said battery to said motor and to said unloading means, and an air operated switch disposed in the path of the air flowing over said engine for controlling the flow of electricity to said compressor unloading means and to said electric motor.

10. In a portable self-contained unit for conditioning air in an airplane or the like, a chassis, an engine mounted on said chassis, a battery, means for supplying electrical energy from said battery to the ignition system of said engine, a compressor mounted on said chassis, power transmitting means between said engine and said compressor, a condenser mounted on said chassis, an evaporator removably supported on said chassis, fan means for flowing air to be conditioned in thermal exchange with said evaporator refrigerant flow connections between said evaporator, condenser and compressor including a multiple passage flexible refrigerant conduit, and conductor means embedded within said conduit leading from said battery and said fan means.

11. In a portable self-contained unit for conditioning air in an airplane or the like, a chassis, an engine mounted on said chassis, a battery, means for supplying electrical energy from said battery to the ignition system of said engine, a compressor mounted on said chassis, power transmitting means between said engine and said compressor, a condenser mounted on said chassis, an evaporator removably supported on said chassis, fan means for flowing air to be conditioned in thermal exchange with said evaporator, refrigerant flow connections between said evaporator, condenser and compressor including a multiple passage flexible refrigerant conduit, conductor means embedded within said conduit leading from said battery and said fan means, and means responsive to a predetermined increase in speed of said engine for initiating the flow of electricity from said battery to said fan means.

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